The present invention relates to a power-source apparatus for a vehicle equipped with a generator and a control method of the same, and, in particular, to a power-source apparatus for a vehicle and a control method of the same which can provide a vehicle traveling having a high fuel economy at an initial use stage of a power source and also keep an appropriate vehicle-traveling state for a long use term of the vehicle.
Recent years, a vehicle, such as an automotive vehicle, which has a function of regenerating deceleration energy at a power-storage device, e.g., a capacitor, at the time of deceleration of the vehicle and utilizing the regenerated energy as a power supply to electric devices, in addition to improving combustion of an engine, reducing vehicle weight and so on, in order to improve the fuel economy (gas mileage), has been put to practical use.
The above-described capacitor, however, generally has a problem in that if the voltage of the capacitor at the time of storing the power is high, the capacitor deteriorates promptly, so that the capacity (i.e., the electrostatic capacity) of the capacitor decreases quickly.
Japanese Patent Laid-Open Publication No. 2005-268122, for example, shows a technology that when an electric system is stopped, the power required for a start of the electric system is set at a low voltage in accordance with a degree of deterioration of the capacitor, and this power for the start is stored at the capacitor in order to restrain progress of deterioration of the capacitor.
Meanwhile, a vehicle having an idling-stop function which is capable of automatically stopping an engine on a specified condition during a temporary stop for a traffic signal or the like in order to improve the fuel economy has been put to practical use. According to the vehicle having the idling-stop function, in the case of using the capacitor as a power-storage device, the more the power stored at the capacitor is, the longer the idling stop lasts, so that the fuel economy can improve properly.
However, in order to achieve the long-term idling-stop operation, it may be necessary that the voltage of the capacitor is set at a higher voltage and this voltage is stored previously during a soak where the vehicle is not used, for example. Therefore, the capacitor may deteriorate promptly, so that capacity of the capacitor may decrease quickly. Consequently, the necessary durability as the power-storage device of the vehicle may not be ensured.